From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Experimental procedure report on measuring brake drum temperature and cooling characteristics.
| Identifier | ExFiles\Box 120\1\ scan0302 | |
| Date | 28th February 1941 | |
| EXPERIMENTAL PROCEDURE. Temperature measurement throughout the following tests was by means of thermo-couples, the hot junctions of which were screwed into small brass pads which were pressed against the drum surface opposite the Girling expanders or hydraulic wheel cylinders by means of springs fitted between the leading shoe and its lining (see Figure A). The wires were taken through a small hole in the dust excluder and, by way of floor-boards or holes in the scuttle, to a switch box on the floor of the car, in front of the passenger seat where all four "cold" junctions were located alongside a thermometer. A galvanometer was connected to the switchbox, which was so arranged that the temperature of any of the four brake drums could be read on the same instrument. DIAGRAM TEXT: DIRECTION OF ROTATION OF DRUM. BRASS PAD. THERMO COUPLE HOT JUNCTION SPRING FIG A.{Mr Adams} METHOD OF FITTING THERMO COUPLE IN DRUM. We considered that the fairest way of comparing the cooling characteristics of the same drums under a variety of conditions was to take cooling curves from a safe maximum temperature of 200° C. to preserve the linings. From these cooling curves, we then plotted the rates of cooling at a given temperature against the speed of the car, thus providing a clearer picture of the conditions. It was soon found that the size of the air gap between lining and drum had a very appreciable effect on the figures obtained, a large air gap giving a shorter cooling time, although we suspect that the lining cools down slower under these conditions. This effect is illustrated in Figure 2, and at all times these adjustments were checked before runs. THE EFFECT ON DRUM COOLING OF THE TYPE OF WHEEL. Tests were carried out on the Coupe first with wire wheels and then with Ace discs fitted to the outside of the same wheels. Finally a "mock-up" disc was fitted on the inside of one wheel, as well as the Ace | ||